NAIROBI, Kenya — The October al-Qaida video shows a light-skinned man handing out food to families displaced by famine in Somalia. But the masked man is not Somali, or even African – he's a Wisconsin native who grew up in San Diego.

A handful of young Muslims from the U.S. are taking high-visibility propaganda and operational roles inside an al-Qaida-linked insurgent force in Somalia known as al-Shabab. While most are from Minnesota, which has the largest Somali population in the nation, al-Shabab members include a Californian and an Alabaman with no ancestral ties to Somalia.

"They are being deployed in roles that appear to be shrewdly calculated to raise al-Shabab's international profile and to recruit others, especially those from the United States and other English-speaking countries," said Anders Folk, a former assistant U.S. attorney who prosecuted suspected al-Shabab supporters in Minnesota.

Officials fear another terrorist attack in East Africa. Kenya announced on Jan. 7 that it had thwarted attempted al-Shabab attacks over the holidays. The same day, Britain's Foreign Office urged Britons in Kenya to be extra vigilant, warning that terrorists there may be "in the final stages of planning attacks."

More than 40 people have traveled from the U.S. to Somalia to join al-Shabab since 2007, and 15 of them have died, according to a report from the House Homeland Security Committee. Federal investigations into al-Shabab recruitment in the U.S. have centered on Minnesota, which has more than 32,000 Somalis.

At least 21 men have left Minnesota to join al-Shabab in that same time. The FBI has confirmed that at least two of them died in Somalia as suicide bombers. A U.S. citizen is suspected in a third suicide bombing, and another is under investigation in connection with a fourth bombing on Oct. 29 that killed 15 people.

The star of the al-Qaida video was Jehad Mostafa, 30, a Californian who handed out food using the name Abu Abdullah al-Muhajir, according to the SITE Monitoring Service. The Washington Post reported last year that Mostafa served as top lieutenant to Saleh Nabhan, a senior al-Qaida operative killed by Navy SEALs in a helicopter attack inside Somalia in 2010.

Mostafa and the Alabaman, Omar Hammami, 27, are among about a dozen men who have been charged in federal court in the U.S. and are believed to be in Somalia.

The Americans appear to have been motivated by the Ethiopian army's intervention in Somalia in 2006, which they saw as an invasion. However, many experts believe it's only a matter of time before al-Shabab turns its wrath on the U.S., which in February 2008 designated it as a terrorist organization. The group killed 76 people in terrorist bombings in Uganda in 2010 during the World Cup final.

U.S. military commanders fear that Americans inside al-Shabab could train as bombmakers and use their U.S. passports to carry out attacks in the United States.

E.K. Wilson, the agent overseeing the FBI's investigation in Minneapolis, said he cannot comment on whether there is an outstanding order to capture or kill Americans fighting for al-Shabab. The FBI has publicly said the Americans should return to the U.S.

It's a mystery what caused Mostafa, a young man whom many remember as mild and friendly, to join an extremist group.

Mostafa grew up in San Diego and graduated from the University of California San Diego. Imam Abdeljalil Mezgouri of the Islamic Center of San Diego, the city's largest mosque, said Mostafa was a respectful teen and good student.

"He was a very quiet, very loving boy. He didn't talk too much but when he did talk, people liked him," said Mezgouri.

Mezgouri said Mostafa got married in his early 20s to a woman he believed was from Somalia.

Public records show Mostafa was the president of the now-defunct Muslim Youth Council of San Diego, or MYCSD. The former organization's Web site says the group was "dedicated to showing the world that Islam is a religion of peace and Muslims are a peaceful and productive part of society."

Mostafa's father, Halim Mostafa, a Kurdish Syrian, is a prominent figure in San Diego's Muslim community who has tried to build bridges with non-Muslims. He made a low-budget film released in 2008 called "Mozlym" to show how the true meaning of Islam is often lost amid the misconceptions of non-Muslims in America, according to the film's Web site.

Edgar Hopida, a spokesman for the San Diego chapter of the Council on American-Islamic Relations, said Halim Mostafa believes in the most liberal interpretation of Islam and noted that "it's ironic if his son is involved with al-Shabab."

Mostafa is believed to have met American militant Anwar al-Awlaki about a decade ago at a San Diego mosque, according to The Washington Post. He went to Somalia in 2005. Federal officials declined to comment.

Mostafa was indicted in August 2010 on terrorism charges for allegedly providing material support to al-Shabab. Mostafa has a leadership role inside al-Shabab and serves as a key liaison to al-Qaida, said Evan Kohlmann, who has assisted government investigations into al-Shabab recruiting and financing.

AP could not reach Mostafa or Hammami for comment. A spokesman for al-Shabab said that the questions AP emailed were "of a personal nature relating to the roles and activities of certain individuals and for that reason they were left unanswered."

The spokesman also said al-Shabab and al-Qaida were "brothers in Islam." He did not provide a name but emailed from an address used by al-Shabab's media outreach wing, which also recently launched a Twitter feed.

The Alabaman, Hammami, 27, has taken on the role of jihadi lecturer and Islamic scholar. After U.S. Navy SEALs killed al-Qaida chief Osama bin Laden in Pakistan earlier this year, Hammami threatened to avenge the killing at a news conference near Mogadishu.

Al-Awlaki's death by a U.S. drone in Yemen in September left Hammami as the most influential U.S. English speaker in the jihadi propaganda sphere, said terrorism expert Ben Venzke. Hammami is also known as Abu Mansour al-Amriki or "the American."

"His more accessible image and manner of speaking may prove a growing and significant threat to not just the region around Somalia but for future attacks on U.S. soil," said Venzke of the Washington-based IntelCenter.

Hammami grew up in Daphne, Ala., a bedroom community of 20,000 outside Mobile known for sunsets on the Gulf of Mexico, seafood and high school football. The phone directory lists 43 Christian churches and not a single Islamic congregation in Daphne.

The son of a Christian mother and a Syrian-born Muslim father, Hammami attended Daphne High School. Then-assistant principal Don Blanchard recalls Hammami as generally well liked.

"Omar I would not classify as a troubled kid," said Blanchard.

Hammami enrolled at the University of South Alabama, where he was president of the Muslim Student Association. Following the 2001 terror attacks, Hammami spoke to the student newspaper.

"Even now it's difficult to believe a Muslim could have done this," The Vanguard quoted Hammami as saying.

Hammami went to Somalia in 2006. He was indicted in 2007 on terrorism charges, and faced more charges in 2009 for providing material support to terrorists.

Hammami, who wears a long beard and often raps in al-Shabab videos, released a nearly 50-minute lecture in October to commemorate five years with the group. He spouts hatred for "Western oppression." In the video, provided to AP by the IntelCenter, he compares his upbringing in America with his life in Somalia, where he says a microwave – "or even a normal oven" – is a rarity.

The English speaker serves as a recruiter and fundraiser and is one of the top people in charge of al-Shabab's foreign fighters, Kohlmann said.

"He sometimes cries with emotion, which makes others cry with him," said Hassan. He added, "Every new American is asked to convince his friends to come. The Americans' suicide attacks and speeches are meant to attract other Americans."

The Americans helped produce what Venzke calls one of the most sophisticated recruitment videos ever released, featuring Minneapolis men in a July 2008 ambush of Ethiopian troops along a road in Somalia. Another video features a Minneapolis man who appeals to others to join the cause in English.

Al-Shabab does not just recruit from the U.S. Three suspects accused of having ties to al-Shabab are now in prison in Australia and awaiting sentencing for allegedly planning an attack on an Australian military base.

Dozens of U.K. residents have also traveled to Somalia to join al-Shabab, and the British government is concerned that Somalia shows many of the characteristics that made Afghanistan "a seedbed for terrorism."

Rick Nelson, a senior fellow at the Center for Strategic and International Studies in even the possibility of military reprisal might not deter al-Shabab from carrying out an attack inside the United States.

"All the elements are there for it to happen," Nelson said.

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Forliti reported from Minneapolis and Watson from San Diego. Associated Press reporters Jay Reeves in Birmingham, Alabama, Katharine Houreld in Nairobi, Kenya, Abdi Guled in Mogadishu, Somalia and Rod McGuirk in Canberra contributed to this report.